A mobile communication standard 3GPP defines a test in a situation in which there is a large variation in the frequency of a DL signal from a base station.
An example of the test is a high speed train (HST) test. In the HST test, a test device including a fading simulator simulates a situation in which a mobile terminal moves at high speed together with a high-speed moving body, such as a bullet train, and checks whether communication with the mobile terminal can be correctly performed.
In this case, the reception frequency of the mobile terminal with respect to the DL signal increases due to a Doppler effect in a situation in which the mobile terminal approaches the base station. The reception frequency of the mobile terminal with respect to the DL signal decreases due to the Doppler effect in a situation in which the mobile terminal is separated from the base station.
The transmission frequency of an uplink (hereinafter, abbreviated to UL) signal which is transmitted from the mobile terminal to the base station is determined on the basis of the reception frequency of the DL signal in the terminal. However, the detailed structure of the frequency determination process is not defined by the 3GPP standard and varies depending on the terminal manufacturer.
Therefore, it is possible to confirm the frequency follow-up capability of the mobile terminal by transmitting a DL signal to which the same frequency variation as that caused by the Doppler effect to a mobile terminal to be tested, which is fixed at a predetermined position, receiving the UL signal which is transmitted from the mobile terminal in response to the DL signal, storing waveform data for the UP signal, analyzing the stored waveform data to check a frequency variation of the UL signal, and contrasting the frequency variation given to the DL signal with the frequency variation calculated from the waveform data of the UL signal.
For example, Patent Document 1 discloses a technique which tests the mobile terminal using a fading simulator.